1. Field of the Invention
The present invention relates to a semiconductor device with a resin package to enclose a semiconductor chip.
2. Description of the Related Art
FIGS. 5-7 of the accompanying drawings show a conventional package type semiconductor device. The illustrated device includes a first lead 1xe2x80x2, a second lead 2xe2x80x2, a semiconductor chip 3xe2x80x2 and a synthetic resin package 4xe2x80x2 to enclose the chip 3xe2x80x2, the inner portion 1axe2x80x2 of the first lead 1xe2x80x2 and the inner portion 2axe2x80x2 of the second lead 2xe2x80x2. As seen from FIGS. 6 and 7, the inner portion 1axe2x80x2 has a width W1xe2x80x2 which is greater than the width of the remaining portion of the lead 1xe2x80x2. Similarly, the inner portion 2axe2x80x2 has width W2xe2x80x2 which is greater than the width of the remaining portion of the lead 2xe2x80x2. The width W1xe2x80x2 is equal to the width W2xe2x80x2. The chip 3xe2x80x2 is mounted on the enlarged inner portion 1axe2x80x2 of the first lead 1xe2x80x2, while also being connected to the enlarged inner portion 2axe2x80x2 of the second lead 2xe2x80x2. With this structure, the heat generated at the chip 3xe2x80x2 is efficiently conducted to the first and the second leads 1xe2x80x2, 2xe2x80x2, which is advantageous to maintaining the proper function of the device.
However, the enlarged inner portions 1axe2x80x2 and 2axe2x80x2 of the leads 1xe2x80x2 and 2xe2x80x2 are not readily bent when the resin package 4xe2x80x2 is bent upon application of an external force. Thus, unfavorably, a crack may be generated in the bent package 4xe2x80x2 by the rigid inner portions 1axe2x80x2 and 2axe2x80x2. One way to address this problem is to enlarge the height Hxe2x80x2 and/or the width Sxe2x80x2 of the package 4xe2x80x2. The enlargement of the package 4xe2x80x2, however, leads to an increase in size and weight of the resulting semiconductor device.
FIGS. 8 and 9 show another conventional semiconductor device in which a relatively narrow connector 5xe2x80x2 is used for connecting the semiconductor chip 3xe2x80x2 to the second lead 2xe2x80x2. In this device, a crack is less liable to form in the package 4xe2x80x2 since the narrow connector 5xe2x80x2 can be readily bent together with the package 4xe2x80x2. However, the illustrated structure will cause an increase in production cost since the auxiliary connector 5xe2x80x2 must be prepared separately from the first and the second leads 1xe2x80x2, 2xe2x80x2. In addition, since the connector 5xe2x80x2 is not integrally formed with the second lead 2xe2x80x2, the unfavorable heat may not be conducted efficiently from the semiconductor chip 3xe2x80x2 to the lead 2xe2x80x2.
The present invention has been proposed under the circumstances described above, and its object is to provide a semiconductor device free from the above-discussed problems.
According to the present invention, there is provided a semiconductor device which includes: a first one-piece lead including an enlarged end; a semiconductor chip mounted on the enlarged end; a second one-piece lead including a flexible end connected to the chip and an outer end; and a resin package for enclosing the enlarged end, the chip and the flexible end. The first and the second leads may partially project from the package in the opposite directions. To prevent the inner portion of the second lead from damaging the package, the flexible end of the second lead is rendered smaller in width than its outer end projecting from the package.
Preferably, the width of the flexible end of the second lead may be equal to xcex8xc3x97the width of the enlarged end of the first lead, where 0.4xe2x89xa6xcex8xe2x89xa60.6.
Preferably, the length of the flexible end may be greater than half the total length of the second lead.
Preferably, the flexible end may includes a first portion and a second portion, wherein the first portion is connected to the chip via a conductive material, while the second portion extends from the first portion at a predetermined angle. With such an arrangement, the flexible end of the second lead can be sufficiently long without increasing the size of the resin package.
In a preferred embodiment, the first portion of the flexible end may be generally parallel to the enlarged end of the first lead.
Preferably, the first portion of the flexible end may be longer than the second portion, so that the first portion is more flexible than the second portion.
In the preferred embodiment of the present invention, the package includes a top surface and a bottom surface opposite to the top surface, wherein the first portion is disposed closer to the top surface than to the bottom surface.
Preferably, the first and the second leads may be exposed in the bottom surface of the package, so that the two leads are reliably soldered to a printed circuit board.
Other features and advantages of the present invention will become apparent from the detailed description given below with reference to the accompanying drawings.